The objective of this proposal is to gain information about lipid-protein interaction as it occurs both in soluble plasma lipoproteins and in cell membranes. The alpha, beta and delta cytolytic toxins of Staphylococcus aureus have been chosen as probes because they damage the integrity of cell membranes, probably by disrupting the lipoproteins. Soluble plasma lipoproteins have been chosen as a simplified model of the membrane. The results of the interaction of the toxins with the plasma lipoproteins will be defined by chemical analysis of treated lipoprotein and by biophysical techniques which will give data concerning molecular weights, density, size and charge changes of the lipoproteins. These results will be used to guide similar experiments on the interaction of membranes and toxins. In addition to information concerning lipid-protein interaction, data relevant to the species specificity of staphylococcal toxins should be forthcoming from this study.